1. Industrial Application
This invention is related to a new nonlinear optical material and its method of manufacture. This material may be employed to fabricate nonlinear optical devices, such as optical bistable devices, by utilizing its nonlinear optical effects.
2. Prior Art
A new optical material having improved nonlinear optical characteristics and higher responses is strongly desired at present. To attain the desired properties of such a material, organic compounds having D electron systems are well-suited. Such organic compounds are generally considered more advantageous than inorganic compound crystals, in which lattice vibration causes the nonlinear optical effects.
A method to prepare this kind of organic material is to introduce a strong donor-type substituent group and a strong acceptor-type substituent group into molecules having electron conjugates. However, with this method, the Second Harmonic Generation (SHG) effect essential to cause nonlinear optical effects, can hardly be obtained even if molecules having extremely high dipole-moments are prepared. Taking for example a dimolecule case, the reason for this is attributed to a strong tendency to form center-symmetrical crystals wherein the molecular dipole-moments are mutually cancelled because of strong interactions between dipole-moments themselves.